Data storage device and data erasing method

ABSTRACT

A recording medium stores data supplied from an external device. A memory stores an erase program for executing erasing of the data stored in the recording medium. An erasing unit erases the data stored in the recording medium in accordance with the erase program stored in the memory, in accordance with a start instruction for instructing a start of erasing the data supplied from the external device.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a data storage device. Further, the present invention relates to a method of erasing data stored in a data storage device.

[0003] 2. Description of the Related Art

[0004] In a case where to sell or dispose of a computer, the owner of the computer usually formats the hard disk of the computer in order to prevent data stored in the hard disk from being seen by others.

[0005] However, a hard disk format program such as one included in Windows™ does not completely erase data stored in a hard disk.

[0006] To be more specific, the hard disk format program only initializes the administration area in which dates of creating data, data sizes, addresses indicating the storage locations of data, etc. are administrated. In other words, the hard disk format program does not initialize the data area in which data are stored.

[0007] Therefore, even after the hard disk is formatted by the hard disk format program, data are kept in the data area.

[0008] The data kept in the hard disk after being formatted can be read out by, for example, software for restoring data which has been erased by mistake.

[0009] Accordingly, in order to securely prevent data stored in the hard disk from being seen by others, data in the data area need be erased.

[0010] Hence, there have been attempts to completely erase data stored in the hard disk by writing predetermined data upon both the administration area and the data area.

[0011] In this case, the main body of the computer (specifically, the CPU (Central Processing Unit)) designates data to be written upon and locations of data writing. The hard disk writes the data designated by the computer main body on the designated locations.

[0012] When writing of the data on the designated locations is completed, the computer main body designates data to be written upon next and next locations of data writing. The hard disk writes the data designated by the computer main body on the designated locations.

[0013] By repeating this operation, the data stored in the hard disk are completely erased.

[0014] However, according to this method, communications are repeated many times between the computer main body and the hard disk from the start of data erasing until the end. Therefore, if the hard disk has large capacity, there arises a problem that it takes a long time to erase all the data stored.

SUMMARY OF THE INVENTION

[0015] Accordingly, an object of the present invention is to provide a data storage device which erases its stored data in a short time. Another object of the present invention is to provide a data erasing method of erasing data stored in a data storage device in a short time.

[0016] To achieve the above objects, a data storage device according to a first aspect of the present invention comprises:

[0017] a recording medium which stores data;

[0018] a memory which stores an erase program for executing erasing of the data stored in the recording medium; and

[0019] an erasing unit which erases the data stored in the recording medium in accordance with the erase program stored in the memory, in response to a start instruction for instructing a start of erasing the data which is supplied from an external device.

[0020] According to this invention, it is possible to erase the data stored in the data storage device in a short period of time.

[0021] The erasing unit may comprise:

[0022] an output unit which outputs a first data stream for confirming the start instruction to the external device;

[0023] a first determiner which determines whether or not a second data stream which is output from the external device in response to the first data stream output from the output unit coincides with the first data stream; and

[0024] an eraser which erases the data stored in the recording medium, in a case where the first determiner determines that the second data stream coincides with the first data stream.

[0025] The erasing unit may comprise a generator which generates the first data stream randomly.

[0026] The erasing unit may comprise a second determiner which determines whether or not the second data stream has been supplied from the external device within a predetermined period of time after the output unit outputted the first data stream.

[0027] The first determiner may determine whether or not the second data stream coincides with the first data stream, in a case where the second determiner determines that the second data stream has been supplied within the predetermined period of time.

[0028] The recording medium may comprise a data area which stores the data, and an administration area which stores administration information for administrating the data.

[0029] The eraser may write predetermined data upon both of the data area and the administration area, thereby to erase the data stored therein.

[0030] The eraser may comprise:

[0031] a determination unit which determines written data to be written upon the data stored in the recording medium, and a location upon which the written data is to be written, in accordance with the erase program; and

[0032] a writer which writes the written data determined by the determination unit upon the location determined by the determination unit, thereby erases the data stored in the recording medium.

[0033] A data erasing method according to a second aspect of the present invention is a data erasing method of erasing data stored in a data storage device,

[0034] wherein:

[0035] the data storage device stores an erase program for executing erasing of data stored in the data storage device;

[0036] the data erasing method comprises erasing the data stored in the data storage device in accordance with the erase program, in response to a start instruction for instructing a start of erasing the data which is supplied from an external device.

[0037] The erasing may comprise:

[0038] outputting a first data stream for confirming the start instruction from the data storage device to the external device;

[0039] firstly determining in the data storage device whether or not a second data stream which is output from the external device in response to the first data stream coincides with the first data stream; and

[0040] executing erasing of the data stored in the data storage device, in a case where it is determined in the firstly determining that the second data stream coincides with the first data stream.

[0041] The erasing may comprise generating in the data storage device, the first data stream randomly.

[0042] The erasing may comprise secondly determining whether or not the second data stream has been supplied from the external device within a predetermined period of time after the first data stream was output from the data storage device.

[0043] The firstly determining may comprise determining in the data storage device whether or not the second data stream coincides with the first data stream, in a case where it is determined in the secondly determining that the second data stream has been supplied within the predetermined period of time.

[0044] The data storage device may comprise a data area which stores the data, and an administration area which stores administration information for administrating the data.

[0045] The executing may comprise writing by the data storage device, predetermined data upon both of the data area and the administration area, thereby erasing the data stored therein.

[0046] The executing may comprise:

[0047] thirdly determining in the data storage device, written data to be written upon the data stored in the data storage device and a location upon which the written data is to be written, in accordance with the erase program; and

[0048] writing by the data storage device, the written data determined in the thirdly determining upon the location determined in the thirdly determining, thereby erasing the data stored in the data storage device.

BRIEF DESCRIPTION OF THE DRAWINGS

[0049] These objects and other objects and advantages of the present invention will become more apparent upon reading of the following detailed description and the accompanying drawings in which:

[0050]FIG. 1 is a diagram showing a structure of a hard disk and a structure of a computer main body to which the hard disk is connected according to the embodiment of the present invention;

[0051]FIG. 2 is a diagram showing a structure of a recording medium constituting the hard disk shown in FIG. 1; and

[0052]FIG. 3A is a flowchart showing an all data erasing process performed by the computer main body shown in FIG. 1, and FIG. 3B is a flowchart showing an all data erasing process performed by the hard disk shown in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0053] A data storage device according to an embodiment of the present invention will now be explained with reference to the attached drawings.

[0054] The data storage device according to the present embodiment will be installed inside or outside a personal computer or workstation. The data storage device stores data supplied from a computer, or erases all data stored therein completely in response to a instruction from the computer.

[0055] The data storage device will now be explained by employing a hard disk as an example.

[0056] The computer comprises a computer main body 1 including a CPU (Central Processing Unit) and a memory shown in FIG. 1, and an input device and an output device not shown in FIG. 1. The input device comprises a keyboard and a mouse, etc., and the output device comprises a display formed of a CRT (Cathode Ray Tube) or a liquid crystal panel.

[0057] The computer main body 1 has a hard disk interface (I/F) 11 to which a hard disk 2 will be connected, and thus can perform data communication with the hard disk 2.

[0058] The computer main body 1 (specifically, the CPU) performs various processes in accordance with programs stored in the memory, and stores data representing a result of a performed process in the hard disk 2. The computer main body 1 (specifically, the CPU) instructs the hard disk 2 to start erasing all data stored in the hard disk 2, in accordance with an operation of a user.

[0059] The hard disk 2 comprises a recording medium 21, a storage unit 22, and a control unit 23.

[0060] The recording medium 21 is constituted by one or more disk(s) covered with magnetic body. The recording medium 21 has a data area for storing data supplied from the computer main body 1, and an administration area for storing administration information such as a date of creating data, data size, an address indicating storage location of data, etc., as shown in FIG. 2.

[0061] The storage unit 22 is constituted by a RAM (Random Access Memory) and a ROM (Read Only Memory), and stores a program for controlling the operation of the control unit 23.

[0062] The control unit 23 is constituted by a CPU (Central Processing Unit), and is connected to the hard disk interface 11. The control unit 23 controls a motor and a magnetic head (not shown) in accordance with an instruction of the computer main body 1, in order to record data supplied from the computer main body 1 in the recording medium 21. The control unit 23 controls the motor and magnetic head (not shown) in accordance with an instruction of the computer main body 1, in order to completely erase all data stored in the recording medium 21.

[0063] Next, the operations of the computer main body 1 and the hard disk 2 when erasing all data stored in the recording medium 21 will be explained.

[0064] First, a user operates the input device (not shown) to instruct the computer main body 1 to erase all data stored in the recording medium 21.

[0065] In response to the instruction of the user, the computer main body 1 (specifically, the CPU) starts an all data erasing process shown in FIG. 3A in accordance with a program stored in the memory

[0066] First, the computer main body 1 outputs an all data erase command for instructing the start of erasing all data to the hard disk 2 (step S101).

[0067] In response to the all data erase command supplied from the computer main body 1, the control unit 23 of the hard disk 2 starts an all data erasing process shown in FIG. 3B in accordance with a program stored in the storage unit 22.

[0068] First, the control unit 23 generates a random data stream for confirming the instruction to erase all data (step S201).

[0069] Then, the control unit 23 outputs the generated data stream and a confirmation command for confirming the instruction to erase all data to the computer main body 1 (step S202).

[0070] In a case where the computer main body 1 operates properly, the computer main body 1 outputs a data stream identical to the supplied data stream and the above described all data erase command to the hard disk 2, in response to the data stream and the confirmation command from the control unit 23 (step S102).

[0071] In a case where the computer main body 1 does not operate properly, for example, in a case where the computer main body 1 runs out of control, the computer main body 1 does not output the data stream and the all data erase command. Or, the computer main body 1 may output a data stream different from the supplied one to the hard disk 2. Or, the computer main body 1 may output an irrelevant command to the hard disk 2.

[0072] The control unit 23 determines whether or not a data stream and the all data erase command have been sent back from the computer main body 1 within a predetermined period of time after it outputted the data stream and the confirmation command (step S203).

[0073] In a case where it is determined that a data stream and the all data erase command have not been sent back (step S203; NO), the control unit 23 determines that the computer main body 1 does not operate properly, and thus stops the all data erasing process.

[0074] On the contrary, in a case where it is determined that a data stream and the all data erase command have been sent back (step S203; YES), the control unit 23 determines whether or not the sent data stream and the data stream which it outputted in step S202 coincide with each other (step S204).

[0075] In a case where it is determined that the both do not coincide with each other (step S204; NO), the control unit 23 determines that the computer main body 1 does not operate properly, and stops the all data erasing process.

[0076] On the contrary, in a case where it is determined that the both data streams coincide (step S204; YES), the control unit 23 erases all the data stored in the data area and the administration area of the recording medium 21 (step S205).

[0077] Specifically, the control unit 23 writes predetermined data upon the data area and the administration area of the recording medium 21 in accordance with the program stored in the storage unit 22. At this time, the control unit 23 determines the predetermined data and a location on which the predetermined data is written in accordance with the program stored in the storage unit 22. Due to this, the control unit 23 completely erases all the data stored in the data area and the administration area of the recording medium 21.

[0078] As described above, the control unit 23 erases all the data stored in the data area and the administration area of the recording medium 21 in accordance with the program stored in the storage unit 22. Therefore, all that the computer main body 1 has to do is to instruct the start of all data erasing, and it needs not to communicate with the hard disk 2 until the end of all data erasing, once this process starts. As a result, all the stored data can be erased in a shorter time than ever before.

[0079] Further, the control unit 23 confirms the instruction to erase all data, by outputting the data stream and the confirmation command to the computer main body 1. Because of this confirmation, if the all data erase command is output by the computer main body 1 which runs out of control, the data stored in the recording medium 21 is prevented from being erased by error.

[0080] In addition, the present invention can be applied in other ways than erasing all data stored in the hard disk 2. For example, the present invention can be applied to erasing all data stored in a recording medium which can record data magnetically or optically (such as a flexible disk, CD-ROM, etc.).

[0081] Various embodiments and changes may be made thereunto without departing from the broad spirit and scope of the invention. The above-described embodiment is intended to illustrate the present invention, not to limit the scope of the present invention. The scope of the present invention is shown by the attached claims rather than the embodiment. Various modifications made within the meaning of an equivalent of the claims of the invention and within the claims are to be regarded to be in the scope of the present invention.

[0082] This application is based on Japanese Patent Application No. 2001-337542 filed on Nov. 2, 2001 and including specification, claims, drawings and summary. The disclosure of the above Japanese Patent Application is incorporated herein by reference in its entirety. 

What is claimed is:
 1. A data storage device comprising: a recording medium which stores data; a memory which stores an erase program for executing erasing of the data stored in said recording medium; and an erasing unit which erases the data stored in said recording medium in accordance with the erase program stored in said memory, in response to a start instruction for instructing a start of erasing the data which is supplied from an external device.
 2. The data storage device according to claim 1, wherein said erasing unit comprises: an output unit which outputs a first data stream for confirming the start instruction to said external device; a first determiner which determines whether or not a second data stream which is output from said external device in response to the first data stream output from said output unit coincides with the first data stream; and an eraser which erases the data stored in said recording medium, in a case where said first determiner determines that the second data stream coincides with the first data stream.
 3. The data storage device according to claim 2, wherein said erasing unit comprises a generator which generates the first data stream randomly.
 4. The data storage device according to claim 3, wherein: said erasing unit comprises a second determiner which determines whether or not the second data stream has been supplied from said external device within a predetermined period of time after said output unit outputted the first data stream; and said first determiner determines whether or not the second data stream coincides with the first data stream, in a case where said second determiner determines that the second data stream has been supplied within the predetermined period of time.
 5. The data storage device according to claim 4, wherein: said recording medium comprises a data area which stores the data, and an administration area which stores administration information for administrating the data; and said eraser writes predetermined data upon both of the data area and the administration area, thereby erases the data stored therein.
 6. The data storage device according to claim 4, wherein said eraser comprises: a determination unit which determines written data to be written upon the data stored in said recording medium, and a location upon which the written data is to be written, in accordance with the erase program; and a writer which writes the written data determined by said determination unit upon the location determined by said determination unit, thereby erases the data stored in said recording medium.
 7. A data erasing method of erasing data stored in a data storage device, wherein: said data storage device stores an erase program for executing erasing of data stored in said data storage device; said data erasing method comprises erasing the data stored in said data storage device in accordance with the erase program, in response to a start instruction for instructing a start of erasing the data which is supplied from an external device.
 8. The data erasing method according to claim 7, wherein said erasing comprises: outputting a first data stream for confirming the start instruction from said data storage device to said external device; firstly determining in said data storage device whether or not a second data stream which is output from said external device in response to the first data stream coincides with the first data stream; and executing erasing of the data stored in said data storage device, in a case where it is determined in said firstly determining that the second data stream coincides with the first data stream.
 9. The data erasing method according to claim 8, wherein said erasing comprises generating in said data storage device, the first data stream randomly.
 10. The data erasing method according to claim 9, wherein: said erasing comprises secondly determining whether or not the second data stream has been supplied from said external device within a predetermined period of time after the first data stream was output from said data storage device; and said firstly determining comprises determining in said data storage device whether or not the second data stream coincides with the first data stream, in a case where it is determined in said secondly determining that the second data stream has been supplied within the predetermined period of time.
 11. The data erasing method according to claim 10, wherein: said data storage device comprises a data area which stores the data, and an administration area which stores administration information for administrating the data; and said executing comprises writing by said data storage device, predetermined data upon both of the data area and the administration area, thereby erasing the data stored therein.
 12. The data erasing method according to claim 10, wherein said executing comprises: thirdly determining in said data storage device, written data to be written upon the data stored in said data storage device and a location upon which the written data is to be written, in accordance with the erase program; and writing by said data storage device, the written data determined in said thirdly determining upon the location determined in said thirdly determining, thereby erasing the data stored in said data storage device. 